1. Field of the Invention
The present invention relates generally to wireless communication, and in particular, to a relay system and method capable of extending a service area and increasing service capacity of a licensed band (LB) system using unlicensed band (UB) resources.
2. Description of the Related Art
The development and commercialization of various wireless communication technologies requires new frequency bands that do not overlap licensed bands for the existing wireless communication technology, due to the characteristics of wireless communication based on the limited frequency resources. However, almost every frequency band has now been used.
Frequency spectra for wireless communication can be divided into licensed bands (LB) and unlicensed bands (UB). A licensed band wireless communication system (hereinafter LB system) includes an analog cellular system based on Advanced Mobile Phone Service (AMPS), a digital cellular system based on Time Division Multiple Access (TDMA), Code Division Multiple Access (CDMA) and Global System for Mobile Communications (GSM), a Digital Cordless Phones (DCT) system, and a Personal Communication Service (PCS) system, while an unlicensed band wireless communication system (hereinafter UB system) includes Bluetooth®, Wireless Local Area Network (WLAN) based on an IEEE 802.11 standard, and Wireless Metropolitan Area Network (WMAN) based on an IEEE 802.16 standard.
A plan for efficient frequency resource utilization for the next generation wireless communication is currently being discussed, and a standard for utilization of ultra-high frequency (UHF) and very high frequency (VHF) for television (TV) frequencies is now in preparation based on Cognitive Radio (CR) technology, the standard being led by IEEE 802.22 group of Institute of Electrical and Electronics Engineers (IEEE). The CR technology detects unused frequency bands that vary according to region or time, to efficiently utilize the unused frequency bands, and is aimed at efficient utilization of the frequency resources that are increasingly used.
Up to the present, however, there has been proposed no specific resource management method using the CR technology. The use of the characteristics of the UB resources can contribute to the extension of a service area of the LB system that uses the limited resources, and to an increase in the system capacity through traffic load balancing.